Patent GB-763824-A (GB)
Title: Process for the production of organic compounds of aluminium and beryllium
IPC: C07F5/00
Filed: 1952-06-19
Abstract: The invention comprises organo-aluminium compounds of the general formula AlR3, wherein R represents an alkyl radical containing at least 5 carbon atoms, and of the general formula <FORM:0763824/IV(b)/1> wherein R, R1 and R11 represent alkyl radicals at least one of which contains at least 5 carbon atoms and at least one of these radicals differs from the other radicals, and a process for the preparation of hydrocarbon substituted aluminium and beryllium compounds in which a hydride of aluminium or beryllium, or a derivative thereof in which one or more hydrogen atoms have been substituted by monovalent saturated hydrocarbon radicals (as hereinafter defined), is heated with a hydrocarbon mono-olefine or poly-olefine at such a temperature that an addition product of the metallic starting compound and the olefine is formed and decomposition or other secondary changes of the starting materials and of the products do not take place to any substantial extent, the proportions of the reactants and the reaction periods being so chosen that the olefine is added to the metallic starting compound in proportions not exceeding about 6 mols. of olefine per equivalent weight of metal.  By "saturated hydrocarbon radical" is meant a hydrocarbon radical which is free from unsaturation other than aromatic or benzenoid unsaturation.  If one equivalent of aluminium or beryllium is represented by me, the products of the above process using a mono-olefine can be represented by the formula meCnH2nR where n is an integer and R represents a saturated hydrocarbon radical, in the case of a di-olefine the products may be represented by the formul  me.CnH2n-2R and me2CnH2n-2R2, wherein R and n have the above significance, and similar formul  in the case of polyolefines.  When several olefine molecules are added to one meR radical, the products may be represented by the formula me(CnH2n)mR where m is an integer from 1 to about 6 and R and n have the above significance.  Mixed aluminium trialkyls are obtainable by reacting compounds of the general formul  AlH2R and AlHR2, wherein R represents an alkyl radical, with aliphatic mono-olefines to introduce different alkyl radicals.  By this method a secondary residue may be introduced by using 1,2-disubstituted ethylenes, e.g. aluminium diethyl-sec.-butyl is obtained from the reaction of aluminium diethyl and sym.di-methylethylene.  The above process may be modified in that the aluminium or beryllium containing reactant is employed in the form of a complex compound thereof with an alkali metal hydride, an alkali metal alkyl or an alkali metal aryl or in the form of an addition compound thereof with an ether, a tertiary amine or a thio-ether. Suitable aluminium and beryllium containing reactants are aluminium and beryllium hydride, lithium aluminium hydride, aluminium alkyl dihydrides, aluminium dialkyl hydrides, beryllium alkyl hydrides, aluminium trialkyls and triaryls, beryllium dialkyls, lithium aluminium tetra-alkyls, sodium aluminium trialkyl hydrides, and aluminium trialkyl and beryllium dialkyl etherates and similar complex compounds formed from tertiary amines and thio-ethers.  The olefine compound used in the above process may be a cyclic olefine having a double bond in a non-aromatic, isocyclic ring, e.g. cyclohexene, or it may be an olefine which contains an aromatic or non-aromatic isocyclic hydrocarbon substituent.  The metal atom always adds on to the carbon atom of the olefine which is richest in hydrogen as exemplified below: <FORM:0763824/IV(b)/2> In the case of vinyl D 3,4-cyclohexene, the vinyl radical mainly reacts with the vinyl radical, and in the case of dicyclopentadiene the double bond in the endocyclic ring reacts readily with aluminium hydride or trialkyl aluminium.  A preferred procedure is to heat aluminium hydride, where necessary under pressure, to temperatures between 30 DEG  and 120 DEG  C. in ethereal solution or in solid form with ethylene or olefines of the general formula <FORM:0763824/IV(b)/3> wherein R1 and R11 represent saturated aliphatic hydrocarbon radicals, the fall in the proportion of olefine in the reaction mixture is followed by observing the fall in pressure or by withdrawing samples, the reaction is interrupted by cooling when 3 mols. of olefine have been reacted for each mol. of aluminium hydride present, and the aluminium trialkyls, or the etherates thereof, formed are isolated by evaporating off the solvent and any excess olefines, and, if desired, the product is further purified by distillation under atmospheric or reduced pressure.  The reacting olefine for this preferred procedure may contain an aromatic or non-aromatic isocyclic hydrocarbon substituent.  For the production of substantially ether-free aluminium compounds starting from ethereal solutions of aluminium hydride by the preferred procedure, the aluminium hydride is, prior to the reaction with the olefine, substantially freed from ether by boiling with an inert saturated aliphatic or aromatic hydrocarbon solvent in the boiling range approximately 40 DEG  to 80 DEG  C. under normal or reduced pressure with continuous withdrawal of distillate and continuous replacement of the distillate withdrawn.  Olefines of the general formula R1-CH = CH2 and <FORM:0763824/IV(b)/4> wherein R1 and R11 may be the same or different and represent alkyl, alkenyl, aryl, aralkyl or cycloalkyl hydrocarbon radicals may be reacted with aluminium hydride in ether, for example CH2 = CH2 forms (CH2CH3)3Al, CH3 CH = CH2 forms (CH3CH2CH2)3Al, CH3CH2 CH2CH = CH2 forms (CH3CH2CH2CH2\t CH2)3Al, (CH3)2C = CH2 forms [(CH3)2 CHCH2]3Al, <FORM:0763824/IV(b)/5> all products being obtained in the form of etherates.  If these products are required ether free, any of the following procedures may be used: (1) the aluminium hydride used is freed from ether before reaction with the olefine and used either as a solid or as a suspension in an inert solvent particularly those having a boiling point higher than 80 DEG  C., such as toluene, xylene and decahydronophthalene, from which suspensions final traces of ether may be removed by boiling. (2) An ethereal solution of a complex aluminium alkali metal tetra-alkyl is first produced either by starting from an ethereal solution of lithium aluminium hydride for reaction with the olefine, or by first adding the olefine to ethereal aluminium hydride and then converting the suspension of aluminium trialkyl etherate into lithium- or sodium-trialkyl aluminium hydride by the addition of lithium hydride or sodium hydride respectively, and on subsequent treatment with the olefine forms on aluminium lithium (or sodium) tetra-alkyl, in each method all traces of ether may be removed by evaporation and then heating in vacuo.  Lithium aluminium tetra-ethyl may be prepared by this method.  The alkali-metal aluminium tetra-alkyls thus produced may then be reacted with 1/3 mol. of aluminium halide in a non-ethereal solvent such as hexane or other saturated aliphatic hydrocarbon to form etherfree aluminium trialkyls.  (3) The reaction between the olefine and the aluminium hydride is interrupted before 3 mols. of the olefine has been taken up to form compounds of the formul  AlH2R and AlHR2, wherein R represents a hydrocarbon radical derived from the olefine plus hydrogen, these compounds do not form stable etherates.  The compounds of the type AlH2R and AlHR2 are then reacted with aliphatic mono-olefines to produce ether-free aluminium trialkyls.  Aluminium trialkyls and aluminium triaryls may also be reacted with olefines, particularly olefines of the general formula R1-CH = CH2, wherein R1 represents a saturated hydrocarbon radical which may contain an aromatic or a non-aromatic isocyclic hydrocarbon substituent, preferably at a temperature of 100 DEG  to 140 DEG  C., e.g. diethyl butyl-, ethyl dibutyl- and tributyl-aluminium can be formed successively from the reaction of aluminium triethyl and ethylene, at a temperature in the preferred range it is possible to obtain hexyl dibutyl-, dihexyl butyl- and trihexyl-aluminium, and aluminium tripropyl, which may be obtained from the reaction of aluminium trimethyl and ethylene or from the reaction of aluminium hydride and propylene, can be reacted with ethylene to form triamyl aluminium. Thus, in this type of reaction mixtures of compounds of the general formula <FORM:0763824/IV(b)/6> wherein m, n and p represent whole numbers up to about 6, are obtainable.  In the reaction of aluminium or beryllium aryls and olefines, the aryl radical adds on to the double bond of the olefine, e.g. in the case of ethylene and a phenyl aluminium, a compound is formed containing the C6H5CH2CH2- radical attached to the aluminium.  If it is desired to build up high molecular weight compounds, it is preferable to react beryllium dialkyls with the olefines, e.g. a beryllium dialkyl may be reacted with an unsymmetrical 1,1-dialkylated ethylene as follows: <FORM:0763824/IV(b)/7> In the examples aluminium hydride is reacted with isobutylene and butene-(1); lithium aluminium hydride is reacted with a -hexene to form a lithium aluminium tetra-hexyl which is then reacted with aluminium chloride to form aluminium trihexyl; lithium aluminium tetraoctyl is prepared in a similar manner using octene-(1); sodium aluminium tripropyl hydride is reacted with propylene to form sodium aluminium tetra-propyl which is then reacted with aluminium chloride to form aluminium tripropyl; aluminium diethyl hydride (obtainable by the reaction of lithium hydride and diethyl aluminium chloride) is reacted with pentene-(2), dicyclopentadiene, butadiene and styrene; dimethyl fulvene is reacted with lithium aluminium hydride and with aluminium diethyl hydride; aluminium triethyl is reacted with ethylene and with octene-(1); and beryllium diethyl is reacted with 2-methyl-pentene-(1).  Preparation of compounds from organoaluminium and beryllium